U.S. patent number 7,810,312 [Application Number 11/785,590] was granted by the patent office on 2010-10-12 for heat exchanger arrangement.
This patent grant is currently assigned to Rolls-Royce plc. Invention is credited to Martyn Richards, Richard G Stretton.
United States Patent |
7,810,312 |
Stretton , et al. |
October 12, 2010 |
Heat exchanger arrangement
Abstract
In certain circumstances recovery of a fluid flow presented
through a heat exchanger into another flow can create problems with
respect to drag and loss of thrust. In gas turbine engines heat
exchangers are utilized for providing cooling of other flows such
as in relation to compressor air taken from the core of the engine
and utilized for cabin ventilation and de-icing functions. By
providing an outlet valve through an outlet duct in a wall of a
housing the exhaust fluid flow from the heat exchanger can be
returned to the by-pass flow with reduced drag effects whilst
recovering thrust. The valve may take the form of a flap
displaceable into the by-pass flow before an exit plan to create a
reduction in static pressure drawing fluid flow through the heat
exchanger.
Inventors: |
Stretton; Richard G
(Loughborough, GB), Richards; Martyn (Burton on
Trent, GB) |
Assignee: |
Rolls-Royce plc (London,
GB)
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Family
ID: |
36580894 |
Appl.
No.: |
11/785,590 |
Filed: |
April 18, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070245738 A1 |
Oct 25, 2007 |
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Foreign Application Priority Data
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Apr 20, 2006 [GB] |
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0607771.3 |
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Current U.S.
Class: |
60/266; 60/267;
60/782; 60/785; 60/806; 60/226.1 |
Current CPC
Class: |
F02C
7/141 (20130101); F02K 3/06 (20130101); F02K
3/115 (20130101); Y02T 50/671 (20130101); Y02T
50/675 (20130101); Y02T 50/60 (20130101) |
Current International
Class: |
F02K
99/00 (20090101) |
Field of
Search: |
;60/226.1,266,267,782,785,806 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2 208 702 |
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Apr 1989 |
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GB |
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2 224 080 |
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Apr 1990 |
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GB |
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Primary Examiner: Cuff; Michael
Assistant Examiner: Kim; Craig
Attorney, Agent or Firm: Melcher; Jeffrey S. Manelli Denison
& Selter PLLC
Claims
The invention claimed is:
1. A gas turbine engine comprising: a bypass duct for a bypass
fluid flow; and a heat exchanger arrangement mounted within a wall
structure over which the bypass fluid flows during operation of the
engine, the wall structure comprises: an inlet for supplying a
coolant fluid flow to the heat exchanger during operation of the
engine; and a duct leading to an outlet valve, wherein the outlet
valve is moveable between an open position and a closed position,
in the open position the outlet valve allows coolant fluid flow
through the heat exchanger and in the closed position prevents
coolant fluid flow through the heat exchanger, in the open position
the valve protrudes into the bypass fluid flow to generate a
reduction in static pressure therein to draw the coolant fluid flow
through the heat exchanger during operation of the engine.
2. A gas turbine engine as claimed in claim 1 wherein the outlet
valve is upstream of a fan nozzle exit plane.
3. A gas turbine engine as claimed in claim 1 wherein the engine
comprises a housing and the outlet valve is in a wall of the
housing.
4. A gas turbine engine as claimed in claim 1 wherein the outlet
valve comprises a flap rotatable about its upstream edge.
5. A gas turbine engine as claimed in claim 1 wherein the static
pressure is variable by specific displacement of the valve.
6. A gas turbine engine as claimed in claim 1 wherein the valve is
opposite a shroud wall providing a fixed cross-sectional area
within which the valve is operable.
7. A gas turbine engine as claimed in claim 1 wherein the wall
structure is any one of a housing, a mounting structure, or a
bifurcation structure.
8. A gas turbine engine as claimed in claim 6 wherein in the open
position the outlet valve defines a converging passage with the
shroud wall.
9. A gas turbine engine as claimed in claim 1 wherein the bypass
duct comprises radially inner and outer walls and the outlet valve
extends radially between the inner and outer walls.
10. A gas turbine engine as claimed in claim 9 wherein the outlet
valve extends the complete radial height of between the walls.
11. A gas turbine engine as claimed in claim 4 wherein the flap is
moveable between the closed position and the open position via an
actuation mechanism comprising a motor and a drive arm connected to
the flap.
12. A gas turbine engine as claimed in claim 3 wherein the heat
exchanger includes a fan air valve and the outlet valve comprises a
flap in kiss-seal engagement with the housing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to GB 0607771.3, filed 20 April
2006 and currently issued under United Kingdom Patent No.
2,437,377.
BACKGROUND OF THE INVENTION
The present invention relates to heat exchanger arrangements and
more particularly to heat exchanger arrangements utilised in gas
turbine engines for cooling fluid flows such as with respect to
ventilation air or oil within the engine or for de-icing.
Operation of gas turbine engines is well known and incorporates
significant fluid flows including compressed air provided by the
compressor fans of that gas turbine engine. This compressed air
flow is bled for a number of functional operations and in
particular in order to provide through an appropriate heat
exchanger cooling of other fluid flows such as the ventilation air
in the cabin of an aircraft associated with a gas turbine engine or
potentially with respect to fuel or lubricating oil coolers in the
engine. The coolant flow, as indicated, is tapped or bled from the
engine flows and returned at an appropriate location within the
engine to maintain a pressure drop sufficient to provide the
necessary cooling function within the heat exchanger with respect
to the ventilation air or other fluid flow through that heat
exchanger. The ventilation air itself is generally taken from
hotter core compressor stages of the engine and so needs cooling at
least during certain engine cycles.
Prior Art FIGS. 1 and 2 respectively illustrate a schematic side
view of a prior heat exchanger arrangement (FIG. 1) and a plan view
(FIG. 2) in the direction of A of the heat exchanger arrangement
depicted in Prior Art FIG. 1. Thus, the arrangement 1 includes a
fluid flow 2 taken from compressor stage 3 air flow generally after
a guide vane 4. The bled fluid flow 2 is regulated by a fan air
valve 5 such that the fluid flow passes as a coolant through a heat
exchanger 6 which exchanges heat with typically another fluid
delivered through ducting 7 (shown in broken line). This other
fluid is generally a cooled air flow which may be used as the
ventilation air for the cabin of an aircraft associated with a gas
turbine engine. The fluid flow 2 having been regulated by the valve
5 and passing through the heat exchanger 6 is exhausted as an
exhaust flow 8 out of the heat exchanger 6. The heat exchanger 6
and valve 5 are located within a wall 15 of a housing 14, usually
known as a splitter fairing, which is generally part of the core
nacelle fixing structure of an engine. The exhausted flow 8 mixes
with a ventilation flow 13 in a zone 11 that is located radially
inwardly of a core cowling 9 and surrounding the engine. In such
circumstances the prior heat exchanger arrangement depicted in
Prior Art FIGS. 1 and 2 has a number of disadvantages particularly
in relation to increasing the temperature in the zone 11 between
the housing incorporated in the heat exchanger 6 and surrounding
parts of the engine as well as a necessary large vent exit area 12
to generate the desired pressure drop across the heat exchanger
resulting in drag to a main propulsive flow 10 when flow through
the heat exchanger 6 is low.
In the above circumstances although dumping of the exhaust flow 8
appears to be a relatively simple procedure, there are a number of
problems. It will be understood that the exit area 12 has to be
sized to cope with the combined ventilation flow 13 and the highest
heat exchanger exhaust flow 8 which means that, typically at
cruise, when the heat exchanger is operating at low or zero levels
it is not possible to recover thrust from this part of the engine
as the vent 12 area is effectively oversized. This over sizing also
creates a drag penalty as the vent area 12 acts as an aero dynamic
step or discontinuity when it is not passing full flow. It will
also be understood that extra heat input into the zone 11 requires
considerable shielding and heat resistance cabling for the core
mounted systems. It will also be understood that by provision of
the valve 5 and therefore switchable nature with regard to the flow
through the heat exchanger 6 it is difficult to tune the flow
regimes in the event of a fire to ensure extinguishants achieve the
required density in all parts of zone 11.
SUMMARY OF THE INVENTION
In accordance with aspects of the present invention there is
provided a heat exchanger arrangement for a gas turbine engine, the
arrangement comprising a fluid flow presented to a heat exchanger
at an inlet and the heat exchanger incorporated within a housing
over which in use the fluid flow passes, the arrangement
characterised in that the heat exchanger has a duct to an outlet
valve and the outlet valve is displaceable into the fluid flow to
generate a reduction in static pressure in use to draw fluid flow
through the heat exchanger.
Generally, the outlet valve is upstream of a fan nozzle exit
plane.
Typically, the outlet valve is in a wall of the housing.
Advantageously, the outlet valve comprises a hinged flap.
Generally, the static pressure is variable by specific displacement
of the valve.
Generally, the valve is opposite a shroud wall providing a fixed
cross-sectional area within which the valve is operable.
Generally, the heat exchanger is for cooling an other fluid flow.
Typically, the other fluid flow is ventilation air or oil.
Typically, the housing comprises a mounting nacelle for a gas
turbine engine.
The invention also includes a gas turbine engine including an
arrangement as described above.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be described by way
of example only with reference to the accompanying drawings in
which:
FIG. 1 is a schematic side view of a prior art heat exchanger
arrangement;
FIG. 2 is a plan view in the direction of A of the prior art heat
exchanger arrangement depicted in FIG. 1;
FIG. 3 is a schematic side view of a first embodiment of a heat
exchanger arrangement in accordance with aspects of the present
invention;
FIG. 4 is a schematic plan view in the direction B of the
arrangement depicted in FIG. 3 with an outlet valve in an open
configuration;
FIG. 4a is a section X-X in FIG. 5 of the outlet valve;
FIG. 5 is a schematic plan view in the direction B of the
arrangement depicted in FIG. 3 with an outlet valve in a closed
configuration;
FIG. 6 is a schematic side view of a second embodiment of a heat
exchanger arrangement in accordance with aspects of the present
invention;
FIG. 7 is a schematic plan view in the direction of arrowhead C of
the heat exchanger arrangement depicted in FIG. 6;
FIG. 7a is a section X-X in FIG. 7 of the outlet valve;
FIG. 8 is a schematic side view of the second embodiment of the
heat exchanger depicted in FIGS. 6 and 7 in an open configuration;
and,
FIG. 9 is a schematic plan view of the heat exchanger depicted in
FIGS. 6 to 8 in a closed configuration.
FIG. 9a is a section X-X in FIG. 9 of the outlet valve.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with aspects of the present invention a heat
exchanger 26 acting as a pre-cooler system for a gas turbine engine
is arranged such that the coolant fluid flow exhaust is kept
separate from the zone 11. Nevertheless, an important factor to
achieve appropriate heat exchanger operation is to provide an
adequate pressure drop across the heat exchanger, that is to say
from the coolant inlet to the coolant outlet sides. Previously such
a pressure drop necessitated the exhausts of the coolant to be
ducted downstream of the nozzle exit plane (45) where the adequate
reduction in static pressure can be achieved. It will be understood
that through the various compressor stages of a gas turbine engine
compressed air flows increase and therefore by appropriate ducting
to higher flow rates the coolant flow can be sucked through the
heat exchanger.
By aspects of the present invention a reduction in static pressure
is achieved without requiring considerable ducting which would
otherwise introduce problems with respect to weight and flow
losses. In accordance with aspects of the present invention the
coolant fluid flow from the heat exchanger is injected into a fan
by-pass flow relatively close to the heat exchanger through an
outlet valve. This outlet valve is configured through its geometry
to generate a reduction in static pressure at the exhaust side to
create the required pressure drop through the heat exchanger.
FIGS. 3 to 5 illustrate a first embodiment of a heat exchanger
arrangement 21 in accordance with aspects of the present invention.
Thus, the arrangement 21 has a heat exchanger 26 to act as a
pre-cooler for another fluid such as the ventilation air for the
cabin of an aircraft. Conduits for that other cooled fluid are
shown by broken lines 27a , 27b in FIG. 3. The heat exchanger 26
receives a coolant fluid flow 22 through an inlet 25. The
regulating fan air valve, as with the previous arrangement depicted
in prior art FIGS. 1 and 2 is not required and therefore removed.
The heat exchanger 26 receives the coolant fluid flow 22 and
exhausts that flow through ducting 35 to an outlet valve 36. This
valve 36 is shown schematically in FIG. 3 and as more closely
depicted in FIGS. 4 to 5 and extends into a by-pass fluid flow 32
in order to generate a reduction of static pressure and so suck
coolant flow 22b through the heat exchanger 26.
By provision of a heat exchanger geometry and particularly in
respect of the exhaust duct 35 with a variable flap valve 40 acting
as the outlet valve 36 it will be understood that the efficiency of
the heat exchanger 26 can be maintained by the pressure drop across
that heat exchanger 26 between the inlet duct 25 and the outlet
duct 35 without the necessity of long conduits to downstream
by-pass flow areas of an engine.
The coolant flow 22 is generally generated by a compressor fan 23
and is part of the propulsive fan flow 32. The heat exchanger 26 as
well as the ducting 35 and outlet valve 36 are generally mounted
within the wall structure 15 of an inner nacelle housing 14
(splitter fairing) or mounting structure or pylon 84, as shown in
FIG. 1, for an engine. The wall structure 15 is a bifurcation
structure, commonly located at top and/or bottom of the engine when
wing mounted, and which spans the bypass duct 80.
The outlet valve 36 extends radially between the bypass duct's
radially inner and outer walls 82, 81 respectively. The outlet
valve 36 may extend the complete radial height of between walls 81,
82, but in this example the valve 36 extends over part of the
radial height.
During heat exchanger operation, the variable flap 40 of the outlet
valve 36 protrudes into the fan by-pass flow 32. In the first
embodiment depicted in FIGS. 3 to 5, a portion 32a of this by-pass
flow 32 is enclosed between the housing wall 15 and a shroud wall
39. The velocity of the portion of flow 32a increases as the
variable flap 40 protrudes and reduces the flow area, particularly
at the valve's outlet. Increasing speed of the by-pass fan flow 32
adjacent to the valve 36 drops the static pressure at an exhaust
plane of the valve 36 creating a suction effect which increases the
pressure drop across the heat exchanger 26 so driving coolant fluid
flow through that heat exchanger 26. It will be understood that in
a preferred embodiment the outlet valve comprises a flap hinged to
one side and displaceable to vary the degree of protrusion into the
by-pass flow 32 and so allows alterations with respect to the
suction effect as a result of the pressure drop across the heat
exchanger 26. This variation in the valve 26 will allow
optimisation with respect to cooling requirements.
It will also be understood as the exhaust flow 22b from the heat
exchanger 26 does not interfere with the ventilation zone flows
(zone 11 in prior art FIG. 1). Thus for the arrangement of the
present invention, over-sizing of the vent outlet 12 is not
required and a suitably sized outlet 12 is used for maximum thrust
recovery and/or flow disturbance from the ventilation air flow.
It will be noted that the outlet valve 36 is located upstream of a
fan nozzle exit plane 45 (FIGS. 3 and 4). Such position ensures
that there is thrust recovery if required.
FIG. 4 and FIG. 5 illustrate respectively open and closed
configurations with regard to heat exchanger arrangements in
accordance with the first embodiment of the present invention. As
described previously, a fluid flow 22 acts as a coolant for the
heat exchanger 26 and this is exhausted through a duct 35 such that
an outlet valve 36 including the variable flap 40 can create
variation in the static pressure, at the duct's outlet, to suck
fluid flow 22 through the heat exchanger 26.
In FIG. 4 the flap 40 is in an open configuration such that fluid
flow 22b is drawn through an aperture 41 between the flap 40 and
parts of the duct 35 or housing 15. This flow through the heat
exchanger 36 will provide a cooling effect with regard to another
flow such as compressor air from the turbine stages of an engine to
be used for cabin ventilation or de-icing. The flap 40 position
creates a low static pressure, local to and importantly immediately
downstream of the flap 40, in a by-pass duct 80 created between the
housing 15 and a shroud wall 39 as described previously. This
variation in static pressure will act to regulate the fluid flow 22
instead or as well as of the previous fan air valve (5 in prior art
FIG. 1 and prior art FIG. 2).
FIG. 4a shows the outlet valve 36 in the direction X-X. Thus, as
can be seen, the flap 40 protrudes into the gap between the shroud
39 and parts of the housing wall 15 in order to present the
aperture 41 through which flow 22b passes when drawn as a result of
the reduced static pressure.
By having a fixed shroud wall 39 and wall 15 it will be understood
that a well-defined flow 32 conduit is created local to the flap 40
giving greater control of the flow conditions adjacent to the duct
35 exhaust. In such circumstances the disturbance as a result of
the flap 40 protruding into that conduit will create the desired
variations in static pressure and therefore flow rate through the
heat exchanger 26. When the flap is forced into a closed
configuration as depicted in FIG. 5, it will be understood that
there will be no fluid flow 22 through the duct 25 to the heat
exchanger 26. The flap is closed, therefore there will be no flow
22b through the conduit 35 and in such circumstances normal fan
flow 32 can be presented without any drag or impingement as a
result of the exhaust flow 22b from the heat exchanger 26 as
described previously. By such an approach the prior necessity of
having an outlet vent which is appropriately sized for highest
expected conditions is avoided. Fluid flow 22 through the heat
exchanger 26 can be adjusted dependent upon actual requirements and
this flow recovered in combination with the by-pass flow 32 for
greater engine efficiency. By providing a fixed shroud wall 39 it
will be understood that an accentuation of the static pressure
reduction effects of flap 40 can be achieved.
The variable flap 40 is rotatable about its upstream edge 40a and
in an open position defines a converging passage 86. Fluid flow 32a
therefore accelerates and creates a low static pressure local to
the outlet plane 41. The variable flap 40 is moveable between a
closed position (FIG. 5) and an open position (FIG. 4) via an
actuation mechanism. One such actuation mechanism comprising a
motor 90 having a drive arm 92 connected to the flap 40. The motor
90 is mounted to a wall of the duct 35. The motor 90 is operable
via electronics as would be understood by the skilled person. The
motor 90 is operable to vary the amount of flow 22b through the
valve 36 to maximise thrust recovery. As the flap 40 may be closed
completely, the flap and drive mechanism 90, 92 is capable of
operating as the inlet valve 5, which in this case is omitted.
Alternatively, a second embodiment in accordance with aspects of
the present invention is depicted in FIGS. 6 to 9. In this
embodiment, an elongated flap is utilised in order to again create
a static pressure reduction to stimulate and regulate fluid flow
through the heat exchanger. As previously, a compressor fan 53
provides a bypass fluid flow 52, part of which fluid flow 52a is
presented to a heat exchanger 56 which in the embodiment depicted
in FIGS. 6 to 9 also includes a fan air valve 55. As previously,
the heat exchanger 56 exhausts an exhaust fluid flow 58 through a
conduit 65 to a valve 66. The fluid flow through the heat exchanger
56 cools another flow generally comprising compressed air in a
conduit 57 in order to act as cabin ventilation or de-icer flows
for operations within an aircraft associated with an engine
incorporating a heat exchanger arrangement 51 in accordance with
aspects of the present invention. The outlet valve 66 is
schematically depicted in FIG. 6 but as can be seen in more detail
in FIG. 7 this valve comprises a hinged flap 70 secured about a
hinge 71.
As described previously with regard to the flap 40 in FIGS. 3 to 5,
the flap 70 is displaceable in order to vary a gap between the
exhaust conduit 65 and parts of a housing 14 within which the heat
exchanger 56 is located. In such circumstances there is a reduction
in the static pressure as a result of fluid flow 78 moving past the
flap 70. This reduction in static pressure will suck fluid flow 52
as a coolant through the heat exchanger 56 for appropriate
operation.
Generally, the flap 70 will be displaceable about the hinge 71 and
come into a kiss seal engagement with parts of the housing 14 and
the duct 65.
In the second embodiment there is no provision of an opposed shroud
wall 39 as depicted in FIGS. 3 to 5 and so the embodiment depicted
in FIGS. 6 to 9 is dependent upon the combination of the fan
by-pass fluid flow 78 and the flap 70 creating sufficient suction
through a static pressure drop without the constraint of a conduit
formed between the housing 14 and an opposed shroud wall such as
wall 39 in FIGS. 3 to 5. In such circumstances as described above,
typically the flap 70 will be more elongate than the flap 40
depicted in FIGS. 3 to 5 in order to take the exhaust flow 58
further downstream to generate sufficient static pressure
reduction. However, the particular advantage of such an arrangement
is that there is less drag/blockage due to deletion of the fixed
shroud wall 39 and housing wall 14 in the first embodiment depicted
in FIGS. 3 to 6. The second embodiment depicted in FIGS. 6 to 9
will require more space for accommodation but as indicated may have
less detrimental effects with regard to drag and blockage. The
particular embodiment utilised for the outlet valve in accordance
with aspects of the present invention will be dependent upon
particular requirements within a gas turbine engine.
FIG. 8 and FIG. 9 respectively show the heat exchanger arrangement
51 as depicted in FIG. 6 and FIG. 7 in an open configuration (FIG.
8) and in a closed configuration (FIG. 9).
In FIG. 8 the fluid flow 52 acts as a coolant for a heat exchanger
56 and is regulated by a fan air valve 55. The exhaust fluid flow
52a is drawn by a pressure differential created by displacement of
the flap 70 about the hinge 71. An end 74 of the flap 70 will be
positioned such that a static pressure reduction is created.
Typically, the end 74 will be arranged to extend towards a fan
nozzle. In such circumstances, fluid flow for cooling effect in the
heat exchanger 56 will be enhanced without providing a blockage to
the by-pass duct in an engine.
FIG. 9 illustrates the heat exchanger arrangement depicted in FIGS.
6 to 8 and, in particular, the arrangement depicted in FIG. 8 in a
closed configuration. Thus, the flap 70 generally lies upon the
housing 14 in order that there is no flow 52a. The flap 70 is in
kiss seal engagement with the wall 15 and possibly an end part 65a
of the outlet ducting 65. In such circumstances between the open
configuration depicted in FIG. 8 and the closed configuration
depicted in FIG. 9 it will be understood that regulation of the
fluid flow for cooling effect within the heat exchanger 56 can be
adjusted with less detrimental effect upon by-pass flow rate in
terms of drag whilst the exhaust flow 22b, 52a can be recovered in
terms of adding to the thrust provided through the by-pass as it is
located before the fan nozzle exit plane 60. It will also be
understood that the fan air valve 55 in the second embodiment
depicted in FIGS. 6 to 9 may be deleted such that fluid flow for
cooling effect in the heat exchanger 56 is achieved generally
through displacing the valve flap or door 70 about the hinge
71.
It will be understood that in accordance with aspects of the
present invention there is a separation between the fluid flow
exhausted from the heat exchanger from the ventilation zone within
the housing for the heat exchanger which is typically the central
nacelle mountings for that engine. This will reduce heating within
the vent zone of that housing, will allow independent optimisation
of vent and heat exchanger exhaust to maximise thrust recovery
whilst minimising drag. Furthermore, for a given by-pass flow rate,
aspects of the present invention will reduce the exhaust static
pressure to increase the pressure drop across the heat exchanger
which in turn should create an improved cooling efficiency within
that heat exchanger. It will also be understood in view of the
selectivity with regard to positioning the outlet valve arrangement
in accordance with the present invention a further means for
controlling flow rate through the heat exchangers is provided in
addition to or in replacement of a fan air inlet valve as utilised
with previous heat exchanger arrangements. Removal of the fan air
inlet valve will enable a more compact design to be achieved with
less blockage and a lighter weight penalty.
As indicated above, aspects of the present invention relate to a
heat exchanger which can be applied to a situation where a coolant
medium, that is to say a fluid flow, is ejected into a moving flow
to minimise drag and constriction whilst facilitating thrust
recovery.
* * * * *